Ubuntu Linux

Ubuntu Linux is the most popular variety of Linux in use on
desktop and laptop systems. It has the backing of a for-profit corporation
(Canonical Inc.), a defined philosophy and a huge and worldwide user base. As
a result, it is a common platform for people who want to use Ardour and other
tools for music creation and pro-audio work.

High Level Recommendations for Ubuntu Users

Currently, installing pro audio applications on vanilla Ubuntu requires some
configuration, in order for the user to gain realtime privilege (read below).
Ubuntu Studio, which is an official flavor of Ubuntu, and thus shares the
repositories with Ubuntu, has this already configured. Other distributions,
such as KXStudio, and Dreamstudio are largely based on Ubuntu, and like
Ubuntu Studio, has these settings preconfigured, while also containing
customized versions of Ubuntu packages, which often are more up to date.

Installing Ardour

There may be unintended differences, and even bugs in Ubuntu native packages,
as a result of a different building method. For this reason, Ardour
developers highly recommend installing the official ready-to-run version of
the program that can be downloaded from ardour.org, as Ubuntu native
packages are not supported in the official Ardour forums or other support
channels.

Click the Permissions tab and check the option "Allow this file to run as
a program".

Close the dialog and double-click the file.

Follow the prompts.

Problems with the interaction between PulseAudio and JACK

Background Info

Like many distributions, Ubuntu has decided to use PulseAudio as
the default audio system. PulseAudio is a rich and capable system that
provides excellent services for typical users of Linux on the desktop.
However, it is not capable of the type of performance that tools like Ardour
require and in particular does not offer the possibility of sending audio
between applications that can make the Linux audio environment a very
interesting one.

This would not be a problem if it were not for the fact that JACK will not
run correctly (if at all) if it needs to use the same soundcard/audio
interface that PulseAudio is using. And since, PulseAudio on Ubuntu is
configured by default to always use the (typically single) audio interface on
the computer, this is a bit of a problem.

The developers of JACK and PulseAudio got together in 2009 and agreed upon a
mechanism by which PulseAudio and JACK could cooperate in their use of a
single soundcard. Whether or not PulseAudio is running by default, when JACK
starts up it sends out a request to use the soundcard. If PulseAudio is
running, it will give up its use of the soundcard to allow JACK to take over
(and can optionally be told to route its own audio through JACK). When JACK
finishes, it sends out another message, and PulseAudio can once again use the
soundcard directly.

What is the problem?

The specific issues known at this time for all flavors of Ubuntu 12.04 and
12.10 are:

a bug in PulseAudio that causes it not to give up the soundcard when JACK
asks (LP:
#1163638, fixed in Ubuntu 13.04).

Symptoms

A message like Cannot start JACK in the output from JACK as it
starts up (though see the next section for other causes of this). This output
may be hidden in the Messages window of QJackCtl (aka JACK Control), so one
should check there.

How to fix

These bugs do not affect releases from 13.04, and earlier releases (12.04 and
12.10) are in the process of being fixed.

Problems with JACK configuration

What is the problem?

To function as intended, JACK needs to run with access to two operating
system facilities called realtime scheduling and memory locking. This means that the user who starts JACK must be
allowed access to these facilities. By default, Ubuntu does create a user
group that has this permission but—it does not put new users into this
group by default. Read more about why here. Consequently,
the user will not have permission to run JACK in the way they should.

Symptoms

A message like Cannot lock down memory in the output from JACK
as it starts up. This output may be hidden in the Messages window of QJackCtl
(aka JACK Control), so one should check there.

How to fix

Make sure the file /etc/security/limits.d/audio.conf exists. If it is named
/etc/security/limits.d/audio.conf.disabled, rename it to the former. Run the
command:

sudo usermod -a -G audio YOUR-LOGIN-NAME

Then log out and log in again. On Ubuntu Studio the user is a member of audio
group by default, but not on other official flavors.

Reporting Issues

Given the difficulties in supporting Ubuntu and the limited time and
resources of the Ardour team, the Ubuntu Studio Project has
requested that issues and bug reports related to Ubuntu, Ubuntu Studio and
other derivitives be directed to them.